The present invention relates to xcex2-amino ketone pro-fragrances which are capable of delivering fragrance raw material ketones, preferably xcex1,xcex2-unsaturated ketones, inter alia, damascones, ionones, to a situs, especially to human.skin wherein said pro-fragrances release the fragrance raw material ketones providing the user with extended aesthetic benefits.
Humans have applied scents and fragrances to their skin since antiquity. Originally these aesthetically pleasing materials were commonly isolated in raw form as resins, gums or essential oils from natural sources, inter alia, the bark, roots, leaves and fruit of indigenous plants. These resins, gums, and oils were directly applied to the body or diluted with water or other solvent, including in some cases, wine. With the advent of modern chemistry, individual components responsible for the odor properties of these resins, gums and oils were isolated and subsequently characterized. Aside from common xe2x80x9cperfume vehiclesxe2x80x9d inter alia, fine perfumes, colognes, eau de toilettes, and after-shave lotions, a wide variety of personal care or personal hygiene items also deliver for aesthetic reasons fragrance notes, accords, or fragrance xe2x80x9ccharacteristicsxe2x80x9d.
It is well known that mixtures of perfume or fragrance raw materials when deposited on the skin lose intensity and may change character with time, mainly due to factors such as differential evaporation and skin penetration. Many attempts have been made to minimize these drawbacks, but so far without notable success. Particularly, efforts have been made to prolong the diffusion, as well as to improve other characteristics of fragrance materials, by e.g. increasing the fragrance raw material concentration or by using additives such as silicones, glycerol, polyethylene glycols and so on. Such additions, however, have never been adequate to increase the longevity of the fragrance odor.
Recently the advent of pro-fragrance and pro-accords have afforded the fine fragrance and perfume formulator with the ability to deliver fragrance raw materials to human skin in a controllable manner thus enhancing the longevity of the fragrance. Most pro-accords inter alia orthoesters, are suitable for delivery fragrance raw material alcohols and esters. Aldehydes and ketones have been delivered via acetals and ketals respectively, however, both of these pro-fragrance materials depend upon the modification of the carbonyl moiety and the rate of ketone fragrance raw material release has been difficult to fine tune to the subtleties of fine fragrance and perfume accords.
Accordingly, there remains a need in the art for a ketone fragrance raw material releasing pro-fragrance which can be formulated into fine fragrances, perfumes, personal care and personal hygiene products wherein the ketone fragrance raw material components can be released in a highly controllable manner to provide enhanced fragrance longevity.
The present invention meets the aforementioned needs in that it has been surprisingly discovered that certain ketone fragrance raw materials inter alia derivatives of ionone and damascone can be controllably released from novel xcex2-amino ketone pro-fragrances. The xcex2-amino pro-fragrances, preferably xcex2-amino ketone pro-fragrances, of the present invention are useful in fragrance delivery systems which deliver fine fragrances with an enhanced perfume longevity.
A first aspect of the present invention relates to compositions comprising:
A) from 0.01% by weight, of a pro-fragrance component comprising:
a) at least 0.01% by weight, of an xcex2-amino ketone pro-fragrance component, said pro-fragrance having the formula: 
xe2x80x83wherein G1 is xe2x80x94CN, xe2x80x94C(O)Y1, xe2x80x94CO2Y1, and mixtures thereof; G2 is G1, Y2, or mixtures thereof, Y1 and Y2 are each independently C1-C18 alkyl, C1-C18 alkenyl, C1-C15 cycloalkyl, C1-C15 cycloalkenyl, C6-C15 aryl, C6-C15 alkyl substituted aryl, and mixtures thereof; R and R1 are each independently C1-C22 substituted or unsubstituted, branched or unbranched alkyl, C2-C22 substituted or unsubstituted, branched or unbranched alkenyl, C2-C20 substituted or unsubstituted, branched or unbranched hydroxyalkyl, C7-C20 substituted or unsubstituted alkylenearyl, C3-C20 substituted or unsubstituted cycloalkyl, alkyleneoxy units having the formula:
xe2x80x94(R4O)xR5
xe2x80x83wherein R4 is C2-C4 alkylene, R5 is hydrogen, C1-C4 alkyl, and mixtures thereof, x is from 1 to 6; C6-C20 aryl, C5-C20 heteroaryl comprising one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and mixtures thereof; two of the units Y1, Y2, R or R1 when taken together form one or more aromatic or non-aromatic, heterocyclic or non-heterocyclic, single rings, fused rings, bicyclo rings, spiroannulated rings, or mixtures thereof, said rings comprising from 3 to 20 carbon atoms and one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and mixtures thereof; and R2 and R3 are hydrogen;
b) at least 0.01% by weight, of an aldehyde or ketone releasing pro-fragrance component, said pro-fragrance having the formula: 
xe2x80x83wherein said pro-fragrance or pro-accord releases an aldehyde or a ketone fragrance raw material, wherein X is oxygen or sulfur; Ra is:
i) C6-C22 substituted or unsubstituted linear alkyl;
ii) C6-C22 substituted or unsubstituted branched alkyl;
iii) C6-C22 substituted or unsubstituted linear alkenyl;
iv) C6-C22 substituted or unsubstituted branched alkenyl;
v) C6-C22 substituted or unsubstituted cycloalkyl;
vi) C6-C22 substituted or unsubstituted branched cycloalkyl;
vii) C6-C22 substituted or unsubstituted cycloalkenyl;
viii) C6-C22 substituted or unsubstituted branched cycloalkenyl;
ix) C6-C22 substituted or unsubstituted aryl;
x) C6-C22 substituted or unsubstituted heterocyclicalkyl;
xi) C6-C22 substituted or unsubstituted heterocyclicalkenyl;
xii) and mixtures thereof;
xe2x80x83Rb is:
i) hydrogen;
ii) C1-C10 substituted or unsubstituted linear alkyl;
iii) C3-C10 substituted or unsubstituted branched alkyl;
iv) C2-C10 substituted or unsubstituted linear alkenyl;
v) C3-C10 substituted or unsubstituted branched alkenyl;
vi) C3-C15 substituted or unsubstituted cycloalkyl;
vii) C4-C15 substituted or unsubstituted branched cycloalkyl;
viii) C4-C15 substituted or unsubstituted cycloalkenyl;
ix) C5-C15 substituted or unsubstituted branched cycloalkenyl;
x) C6-C15 substituted or unsubstituted aryl;
xi) C6-C22 substituted or unsubstituted heterocyclicalkyl;
xii) C6-C22 substituted or unsubstituted heterocyclicalkenyl;
xe2x80x83Ra and Rb when taken together form a substituted or unsubstituted ring having in the ring from 3 to 10 carbon atoms; and
xe2x80x83each Rc, Rd, R6 and each R4 and R5 pair are independently:
i) Rb;
ii) hydroxyl;
iii) a carbonyl comprising unit having the formula:
xe2x80x94(CH2)vCOR7
xe2x80x83wherein R7 is:
a) xe2x80x94OH;
b) xe2x80x94OR8 wherein R8 is hydrogen, C1-C15 substituted or unsubstituted linear alkyl, C1-C15 substituted or unsubstituted branched alkyl, C2-C22 substituted or unsubstituted linear alkenyl, C3-C22 substituted or unsubstituted branched alkenyl, or mixtures thereof;
c) xe2x80x94N(R9)2 wherein R9 is hydrogen, C1-C6 substituted or unsubstituted linear alkyl, C3-C6 substituted or unsubstituted branched alkyl, or mixtures thereof;
d) C1-C22 substituted or unsubstituted linear alkyl;
e) C1-C22 substituted or unsubstituted branched alkyl;
f) C2-C22 substituted or unsubstituted linear alkenyl;
g) C3-C22 substituted or unsubstituted branched alkenyl;
h) C3-C22 substituted or unsubstituted cycloalkyl;
i) C6-C22 substituted or unsubstituted aryl;
j) C6-C22 substituted or unsubstituted heterocyclicalkyl;
k) C6-C22 substituted or unsubstituted heterocyclicalkenyl;
xe2x80x83the index v is from 0 to 22;
iv) alkyleneoxy units having the formula:
xe2x80x94(CR10R11)y(CHR12CHR13O)zR14
xe2x80x83wherein each R10, R11, and R12 is independently;
a) hydrogen;
b) xe2x80x94OH;
c) C1-C4 alkyl;
d) or mixtures thereof;
xe2x80x83R13 is:
a) hydrogen;
b) C1-C4 alkyl;
c) or mixtures thereof;
xe2x80x83R14 is:
a) hydrogen;
b) C1-C4 alkyl;
c) or mixtures thereof;
xe2x80x83R10 and R11 when taken together form a C3-C6 spiroannulated ring, carbonyl unit, or mixtures thereof; y has the value from 0 to 10, z has the value from 1 to 50;
v) any two Rc, Rd, R4, R5, or R6 units when taken together form:
a) a carbonyl moiety;
b) a C3-C6 spiroannulated ring;
c) a heterocyclic aromatic ring comprising from 5 to 7 atoms;
d) a non-heterocyclic aromatic ring comprising from 5 to 7 atoms;
e) a heterocyclic ring comprising from 5 to 7 atoms;
f) a non-heterocyclic ring comprising from 5 to 7 atoms;
g) or mixtures thereof;
vi) and mixtures thereof; and
xe2x80x83the index n is an integer from 1 to 3; and
B) optionally from 1% by weight, a fragrance raw material component comprising:
i) optionally at least 1% by weight, of a mixture of one or more base note fragrances;
ii) optionally at least 1% by weight, of a mixture of one or more top or middle note fragrances;
iii) optionally the balance carriers, fixatives, and other adjunct ingredients.
These and other objects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. All percentages, ratios and proportions herein are by weight, unless otherwise specified. All temperatures are in degrees Celsius (xc2x0 C.) unless otherwise specified. All documents cited are in relevant part, incorporated herein by reference.
The present invention relates to fragrance delivery systems which comprise one or more xcex2-amino ketone pro-fragrances of damascones, ionones and their isomers. The pro-fragrances of the present invention are suitable for use in fragrance delivery systems which are capable in delivering enhanced fragrance benefits to fine fragrances and perfumes as well as personal care and personal hygiene articles.
The xcex2-amino pro-fragrances of the present invention have the formula: 
wherein G1 is xe2x80x94CN, xe2x80x94C(O)Y1, xe2x80x94CO2Y1, and mixtures thereof; G2 is G1, Y2, or mixtures thereof; Y1 and Y2 are each independently C1-C18 alkyl, C1-C18 alkenyl, C1-C15 cycloalkyl, C1-C15 cycloalkenyl, C6-C15 aryl, C6-C15 alkyl substituted aryl, and mixtures thereof; and R2 and R3 are hydrogen.
R and R1 are each independently C1-C22 substituted or unsubstituted, branched or unbranched alkyl, C2-C22 substituted or unsubstituted, branched or unbranched alkenyl, C2-C20 substituted or unsubstituted, branched or unbranched hydroxyalkyl, C7-C20 substituted or unsubstituted alkylenearyl, C3-C20 substituted or unsubstituted cycloalkyl, alkyleneoxy units having the formula:
xe2x80x94(R4O)xR5
wherein R4 is C2-C4 alkylene, R5 is hydrogen, C1-C4 alkyl, and mixtures thereof, x is from 1 to 6; C6-C20 aryl, C5-C20 heteroaryl comprising one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and mixtures thereof; two of the units Y1, Y2, R1 or can be taken together to form one or more aromatic or non-aromatic, heterocyclic or non-heterocyclic, single rings, fused rings, bicyclo rings, spiroannulated rings, or mixtures thereof, said rings comprising from 3 to 20 carbon atoms and one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and mixtures thereof.
In another aspect of Applicants"" invention the xcex2-amino pro-fragrances of the present invention have the formula: 
wherein Y1 and Y2 are each methyl or a cycloalkenyl unit selected from the group consisting of:
i) 2,6,6-trimethylcyclohex-2-enyl having the formula: 
ii) 2,6,6-trimethylcyclohex-1-enyl having the formula: 
iii) 2-methylene-6,6-dimethylcyclohexanyl having the formula: 
iv) 2,6,6-trimethylcyclohex-3-enyl having the formula: 
v) and mixtures thereof;
provided at least one Y1 or Y2 is methyl and both Y1 and Y2 are not each methyl, R and R1 are not both hydrogen.
The following are the common chemical names for the damascones and ionones which are delivered by the pro-fragrances of the present invention; 1-(2,6,6-trimethylcyclohex-2-enyl)-2-butene-1-one(xcex1-damascone), 1-(2,6,6-trimethylcyclohex-1-enyl)-2-butene-1-one(xcex2-damascone), 1-(2-methylene-6,6-dimethylcyclohexanyl)-2-butene-1-one(xcex3-damascone), 1-(2,6,6-trimethylcyclohex-3-enyl)-2-butene-1-one (xcex4-damascone), 4-(2,6,6-trimethylcyclohex-2-enyl)-3-butene-2-one(xcex1-ionone), 4-(2,6,6-trimethylcyclohex-1-enyl)-3-butene-2-one(xcex2-ionone), 4-(2-methylene-6,6-dimethylcyclohexanyl)-3-butene-2-one(xcex3-ionone).
Further preferred ketones which can be delivered by the xcex2-amino ketone pro-fragrances of the present invention include 4-(2,6,6-trimethyl-2-cyclohexen-1-yl)-3-methyl-3-buten-2-one, 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)-1,6-heptandien-3-one, 4-(2,5,6,6-tetramethyl-2-cyclohexen-1-yl)-3-methyl-3-buten-2-one, 2-pentyl-2-cyclopenten-1-one, 2-hexyl-2-cyclopenten-1-one, cis-3-methyl-2-(2-pentenyl)-2-cyclopenten-1-one, 6-(2-propenyl)-5-methyl-2-(1-methylethylidene)cyclohexanone, 4-(4-methoxy)phenyl-3-buten-2-one, 2,5,5-trimethyl-2,6-heptadien-4-one, and 2-methyl-6-(4-methylcyclohex-3-enyl)-2,5-heptadien-4-one.
An example of a xcex2-amino ketone pro-fragrance according to the present invention includes 1-(2,6,6-trimethyl-3-cyclohexen-1-yl)-3-N-(2-hydroxyethyl)-N-phenylmethyl-1-butanone having the formula: 
1-(2,6,6-trimethyl-3-cyclohexen-1-yl)-3-N,N-di(2-hydroxyethyl)-1-butanone having the formula: 
1-(2,6,6-trimethyl-3-cyclohexen-1-yl)-3-N,N-bis(5-hydroxy-3-oxapentyl)-1-butanone having the formula: 
and 2-hexyl-3-di(2-hydroxyethyl)aminocyclopentanone having the formula: 
The fragrance delivery systems of the present invention comprise one or more heterocyclic aldehyde-releasing and/or ketone-releasing pro-fragrances preferably oxazolidines, tertahydro-1,3-oxazines, thiazolidines, or tetrahydro-1,3-thiazines, more preferably oxazolidines, or tertahydro-1,3-oxazines, most preferably oxazolidines.
The pro-fragrances or pro-accords which are suitable for use in the fragrance delivery systems described herein have the formula: 
and are capable of releasing an aldehyde fragrance raw material having the formula: 
or a ketone fragrance raw material having the formula: 
For the purposes of the fragrance delivery systems which comprise one or more heterocyclic pro-fragrances or pro-accords, Ra units are defined herein as:
i) C6-C22, preferably C6-C18, more preferably C6-C15 substituted or unsubstituted linear alkyl; one or more examples of a fragrance raw material which comprises this unit includes nonanal and decanal;
ii) C6-C22, preferably C6-C18, more preferably C6-C15 substituted or unsubstituted branched alkyl; one or more examples of a fragrance raw material which comprises this unit includes 2-methyldecanal;
iii) C6-C22, preferably C6-C18, more preferably C6-C15 substituted or unsubstituted linear alkenyl; one or more examples of a fragrance raw material which comprises this unit includes 10-undecenal;
iv) C6-C22, preferably C6-C15, more preferably C6-C18 substituted or unsubstituted branched alkenyl; one or more examples of a fragrance raw material which comprises this unit includes citral, melonal, and neral;
v) C6-C22, preferably C6-C18, more preferably C6-C10 substituted or unsubstituted cycloalkyl;
vi) C6-C22, preferably C6-C15, more preferably C6-C15 substituted or unsubstituted branched cycloalkyl;
vii) C6-C22, preferably C6-C18, more preferably C6-C15 substituted or unsubstituted cycloalkenyl;
viii) C6-C22, preferably C6-C18, more preferably C6-C15 substituted or unsubstituted branched cycloalkenyl; one or more examples of a fragrance raw material which comprises this unit includes xcex1-damascone and xcex2-ionone;
ix) C6-C22, preferably C6-C18, more preferably C6-C10 substituted or unsubstituted aryl wherein said aryl unit preferably comprises a phenyl unit; one or more examples of a fragrance raw material which comprises this unit includes benzaldehyde, hydrotropaldehyde and vanillin;
x) C6-C22, preferably C6-C15, more preferably C6-C15 substituted or unsubstituted heterocyclicalkyl;
xi) C6-C22, preferably C6-C18, more preferably C6-C15 substituted or unsubstituted heterocyclicalkenyl;
xii) and mixtures thereof;
xe2x80x83Rb is:
i) hydrogen;
ii) C1-C10, preferably C1-C5 substituted or unsubstituted linear alkyl;
iii) C3-C10, preferably C3-C5 substituted or unsubstituted branched alkyl;
iv) C2-C10, preferably C2-C5 substituted or unsubstituted linear alkenyl;
v) C3-C10, preferably C4-G10 substituted or unsubstituted branched alkenyl;
vi) C3-C15, preferably C6-C10 substituted or unsubstituted cycloalklyl;
vii) C4-C15, preferably C6-C10 substituted or unsubstituted branched cycloalkyl;
viii) C4-C15, preferably C6-C10 substituted or unsubstituted cycloalkenyl;
ix) C5-C15, preferably C6-C10 substituted or unsubstituted branched cycloalkenyl;
x) C6-C15, preferably C6-C10 substituted or unsubstituted aryl;
xi) C6-C22, preferably C6-C10 substituted or unsubstituted heterocyclicalkyl;
xii) C6-C22, preferably C6-C10 substituted or unsubstituted heterocyclicalkenyl;
xe2x80x83Ra and Rb when taken together form a substituted or unsubstituted ring having in the ring from 3 to 10 carbon atoms; one or more examples of which are substituted cyclopentanone derivatives inter alia hedione and nectaryl; and each Rc, Rd, R6 and each R4 and R5 pair are independently:
i) Rb;
ii) hydroxyl;
iii) a carbonyl comprising unit having the formula:
xe2x80x94(CH2)vCOR7
xe2x80x83wherein R7 is:
a) xe2x80x94OH, in the case of carboxylic acids;
b) xe2x80x94OR8, in the case of esters wherein R8 is hydrogen; C1-C15, preferably C1-C10, more preferably C1-C4 substituted or unsubstituted linear alkyl; C3-C15, preferably C3-C10, more preferably C3-C4 substituted or unsubstituted branched alkyl; C2-C22, preferably C2-C10, more preferably C2-C4 substituted or unsubstituted linear alkenyl; C3-C22 substituted or unsubstituted branched alkenyl, or mixtures thereof;
c) xe2x80x94N(R9)2 in the case of amides wherein each R9 is independently hydrogen; C1-C15, preferably C1-C10, more preferably C1-C4 substituted or unsubstituted linear alkyl; C3-C15, preferably C3-C10, more preferably C3-C4 substituted or unsubstituted branched alkyl; or mixtures thereof;
d) C1-C22, preferably C1-C5 substituted or unsubstituted linear alkyl;
e) C1-C22, preferably C3-C5 substituted or unsubstituted branched alkyl;
f) C2-C22, preferably C2-C5 substituted or unsubstituted linear alkenyl;
g) C3-C22, preferably C4-C10 substituted or unsubstituted branched alkenyl;
h) C5-C22, preferably C6-C10 substituted or unsubstituted cycloalkyl;
i) C6-C22, preferably C6-C10 substituted or unsubstituted aryl;
j) C6-C22, preferably C6-C10 substituted or unsubstituted heterocyclicalkyl;
k) C6-C22, preferably C6-C10 substituted or unsubstituted heterocyclicalkenyl;
xe2x80x83the index v is from 0 to 22;
v) alkyleneoxy units having the formula:
xe2x80x94(CR10R11)y(CHR12CHR13O)zR14
xe2x80x83wherein each R10, R11, and R12 is independently;
a) hydrogen;
b) xe2x80x94OH;
c) C1-C4 alkyl, preferably methyl;
d) or mixtures thereof; preferably R10, R11, and R12 are each hydrogen;
xe2x80x83R13 is:
a) hydrogen;
b) C1-C4 alkyl, preferably methyl;
c) or mixtures thereof; preferably R13 is methyl or hydrogen, more preferably hydrogen;
xe2x80x83R14 is:
a) hydrogen;
b) C1-C4 alkyl, preferably methyl;
c) or mixtures thereof; preferred R14 is hydrogen;
xe2x80x83R10 and R11 when taken together form a C3-C6 spiroannulated ring, carbonyl unit, or mixtures thereof; y has the value from 0 to 10, z has the value from 1 to 50;
vi) any two Rc, Rd, R4, R5, or R6 units when taken together, and where feasible, combined to form:
a) a carbonyl moiety;
b) a C3-C6 spiroannulated ring;
c) a heterocyclic aromatic ring comprising from 5 to 7 atoms;
d) a non-heterocyclic aromatic ring comprising from 5 to 7 atoms;
e) a heterocyclic ring comprising from 5 to 7 atoms;
f) a non-heterocyclic ring comprising from 5 to 7 atoms;
g) or mixtures thereof;
vii) and mixtures thereof;
xe2x80x83the index n is an integer from 1 to 3, preferably 1 or 2, more preferably 1.
For the purposes of the present invention, the term xe2x80x9csubstitutedxe2x80x9d is defined herein as xe2x80x9ccompatible moieties which replace a hydrogen atomxe2x80x9d. For the purposes of the present invention, hydrogens which are substitutable are labeled as Rxe2x80x2 units in the following examples. Non-limiting examples of substituents which can replace hydrogen atoms are C1-C22 linear or branched hydrocarbyl units inter alia alkyl, alkenyl; hydroxy, nitrilo, nitro, carboxyl (xe2x80x94CHO; xe2x80x94CO2H; xe2x80x94CO2Rxe2x80x3; xe2x80x94CONH2; xe2x80x94CONHRxe2x80x3; xe2x80x94CONRxe2x80x32; wherein Rxe2x80x3 is C1-C12 linear or branched alkyl), amino, C1-C12 mono- and dialkylamino, and mixtures thereof. However, the formulator may wish to include other substituents not specifically mentioned herein. Not each hydrogen of a substituted unit, i.e., substituted linear alkyl, must be substituted; only one hydrogen must be substituted by another moiety for a unit to be xe2x80x9csubstitutedxe2x80x9d for the purposes of the present invention.
The present invention also relates to fragrance raw material delivery systems, said delivery systems comprising:
A) from about 0.1%, preferably from about 0.5%, more preferably from about 1%, yet more preferably from about 5%, most preferably from about 10% to about 100%, preferably to about 75%, more preferably to about 50% by weight, of a pro-fragrance component comprising:
i) at least 0.01%, preferably from about 0.5%, more preferably from about 5%, most preferably from about 25% to about 100%, more preferably to about 75%., most preferably to about 50% by weight, of an xcex2-amino ketone pro-fragrance component according to the present invention;
ii) optionally from about 0.01%, preferably from about 0.5%, more preferably from about 5%, most preferably from about 25% to about 99%, more preferably to about 75%, most preferably to about 50% by weight, by weight, of one or more pro-accords formed from at least one fragrance raw material, wherein said pro-accord is selected from the group consisting of acetals, ketals, orthoesters, orthocarbonates, and mixtures thereof, each pro-accord releasing upon hydrolysis said fragrance raw material from which it is formed, said fragrance raw materials selected from the group consisting of primary, secondary, and tertiary alcohols, aldehydes, ketones, esters, carbonates, and mixtures thereof, provided at least one pro-accord:
a) is formed from at least one fragrance raw material having a molecular weight greater than or equal to about 100 g/mol;
b) has a fragrance release half-life of greater than or equal to about 0.1 hours at pH 5.3 and less than or equal to about 12 hours at pH 2.5 when measured in NaH2PO4 buffer;
iii) the balance carriers, stabilizers, and other adjunct ingredients; and
B) optionally from about 0.01%, preferably from about 0.5%, more preferably from about 1%, yet more preferably from about 5%, most preferably from about 10% to about 99%, preferably to about 75%, more preferably to about 50% by weight, by weight, a fragrance raw material component comprising:
i) optionally at least 0.01%, preferably from about 0.5%, more preferably from about 5%, most preferably from about 25% to about 100%, more preferably to about 75%, most preferably to about 50% by weight, by weight, of a mixture of one or more base note fragrances:
ii) optionally at least 0.01%, preferably from about 0.5%, more preferably from about 5%, most preferably from about 25% to about 100%, more preferably to about 75%, most preferably to about 50% by weight, by weight, of a mixture of one or more top or middle note fragrances;
iii) optionally the balance carriers, fixatives, and other adjunct ingredients.
When used the fragrance delivery systems of the present invention will comprise from about 0.1%, preferably from about 1% to about 100%, preferably to about 85% of the composition depending upon the execution. For example, a fine fragrance may comprise 100% by weight, of a fragrance delivery as described herein, whereas a body lotion or cream may comprise from about 1% to about 5% by weight, of the fragrance delivery system.
For the purposes of the fragrance delivery systems of the present invention, a xe2x80x9cpro-accord which comprises n fragrance raw materials but which releases n+1 fragrance raw materialsxe2x80x9d is defined as xe2x80x9ca compound which is prepared from one or more fragrance raw materials, said fragrance raw material being chemically transformed into a xe2x80x9creleasable formxe2x80x9d such that when said releasable form breaks down, the original fragrance raw material is released as well as at least one other fragrance raw material which was not a starting material used in forming the releasable formxe2x80x9d. The term xe2x80x9creleasable formxe2x80x9d is defined herein as a xe2x80x9cpro-fragrance or pro-accord compound, which ever form is applicablexe2x80x9d. Non-limiting examples of xe2x80x9creleasable formsxe2x80x9d or pro-accords which satisfy the n+1 requirement are as follows.
Preferably the pro-accords of the present invention are orthoesters and orthocarbonates which deliver n+1 fragrance raw materials when the xe2x80x9cpro-accordxe2x80x9d has been formed from n fragrance raw materials. These xe2x80x9cIncreased Releasexe2x80x9d pro-accords are preferably formate, acetate, propionate, and benzoate orthoesters. Any fragrance raw material may be used to form the xe2x80x9cincreased releasexe2x80x9d pro-accord provided the final pro-accord:
a) has a molecular weight greater than or equal to about 300 g/mol;
b) has a molecular weight at least two times greater than the lowest molecular weight fragrance raw material which comprises said pro-accord; and
c) has a fragrance release half-life greater than or equal to about 0.1 hours when measured in NaH2PO4 buffer at pH 5.3 and less than about 12 hours when measured in NaH2PO4 buffer at pH 2.5.
The value of the index n is an integer from 1 to 3.
When present the xe2x80x9cincreased releasexe2x80x9d pro-accords comprise at least 0.01% of the increased fragrance retention composition, preferably at least about 0.1% more preferably at least about 0.5% by weight, of said composition. More than one xe2x80x9cincreased releasexe2x80x9d pro-accords may be combined together as described herein above to provide a complex perfume mixture or accord.
Non-limiting examples of pro-accords which optionally comprise the fragrance delivery systems of the present invention include orthoesters having the formula: 
wherein R is hydrogen, C1-C8 linear alkyl, C4-C20 branched alkyl, C6-C20 cyclic alkyl, C6-C20 branched cyclic alkyl, C6-C20 linear alkenyl, C6-C20 branched alkenyl, C6-C20 cyclic alkenyl, C6-C20 branched cyclic alkenyl, C6-C20 substituted or unsubstituted aryl, and mixtures thereof; R1, R2 and R3 are independently C1-C20 linear, branched, or substituted alkyl; C2-C20 linear,branched, or substituted alkenyl; C5-C20 substituted or unsubstituted cyclic alkyl; C6-C20 substituted or unsubstituted aryl, C2-C40 substituted or unsubstituted alkyleneoxy; C3-C40 substituted or unsubstituted alkyleneoxyalkyl; C6-C40 substituted or unsubstituted alkylenearyl; C6-C32 substituted or unsubstituted aryloxy; C6-C40 substituted or unsubstituted alkyleneoxyaryl; C6-C40 oxyalkylenearyl, and mixtures thereof; or a cyclic orthoester having the formula: 
wherein at least one R4 or R5 is derived from a fragrance raw material alcohol, each X is xe2x80x94C(R6)2xe2x80x94 wherein each R6 is independently hydrogen, C1-C22 linear or branched alkyl, C2-C22 linear or branched alkenyl, C6-C22 substituted or unsubstituted aryl, and mixtures thereof, Y is xe2x80x94CR7R8xe2x80x94, Cxe2x95x90O, and mixtures thereof, wherein R7 and R8 are independently hydrogen, hydroxyl, nitro, nitrilo, C1-C30 substituted or unsubstituted linear alkyl, C3-C30 substituted or unsubstituted branched alkyl, C3-C30 substituted or unsubstituted cyclic alkyl, C2-C30 substituted or unsubstituted linear alkenyl, C3-C30 substituted or unsubstituted branched alkenyl, C3-C30 substituted or unsubstituted cyclic alkenyl, C2-C30 substituted or unsubstituted linear alkynyl, C3-C30 substituted or unsubstituted branched alkynyl, C6-C30 substituted or unsubstituted alkylenearyl, C6-C30 substituted or unsubstituted aryl, C2-C20 substituted or unsubstituted alkyleneoxy, C3-C20 substituted or unsubstituted alkyleneoxyalkyl, C7-C20 substituted or unsubstituted alkylenearyl, C6-C20 substituted or unsubstituted alkyleneoxyaryl, and mixtures thereof, or R7 and R8 can be taken together to form a spiroannulated ring or taken together with any R6 to form a fused ring, said spiroannulated or fused ring having from 3 to 8 carbons and optionally one or more heteroatoms in said ring, said ring further optionally substituted by one or more C1-C22 alkyl, C1-C22 alkenyl, C6-C12 aryl, C6-C22 alkylenearyl units, and mixtures thereof; m is from 0 to 14, p is from 0 to 14, and n is from 0 to 3; provided m+n+p is at least 1 and less than or equal to 14.
Examples of xe2x80x9cincreased releasexe2x80x9d pro-accords which are comprised of a single fragrance raw materials but which release at least 2 fragrance raw materials include but are not limited to tris(citronellyl)orthoformate which releases the binary accord citronellyl formate/citronellol; tris(citronellyl)orthoacetate which releases the binary accord citronellol/citronellyl acetate; tris(geranyl)orthoformate which releases the binary accord geraniol/geranyl formate; tris(geranyl)orthoacetate which releases the binary accord geraniol/geranyl acetate; tris(phenylethyl)orthoformate which releases the binary accord 2-phenylethanol/phenylethyl formate; tris(phenylethyl)orthoacetate which releases the binary accord 2-phenylethanol/phenylethyl acetate; tris(9-decenyl)orthoformate which releases the binary accord 9-decen-1-ol/9-decenyl formate; and tris(9-decenyl)orthoacetate which releases the binary accord 9-decen-1-ol/9-decenyl acetate. For the purposes of the present invention when an orthoester comprises only one fragrance raw material alcohol (releases a binary accord) the terms xe2x80x9ctris(alcohol)orthoesterxe2x80x9d and xe2x80x9calcohol orthoesterxe2x80x9d are used interchangeably. For example, tris(geranyl)orthoacetate stands equally well for geranyl orthoacetate and are considered interchangeable.
The pro-accord tris(9-decenyl)orthoformate is prepared by treating 9-decenol (i.e., Rosalva), which is a fragrance raw material as defined herein, with a suitable amount of triethyl orthoformate, not a fragrance raw material as defined herein, in the presence of an acid catalyst optionally in the presence of a solvent. Tris(9-decenyl) when exposed to suitable conditions (e.g., exposure to the acid mantle of human skin) breaks down to release a mixture of 9-decenol and 9-decenyl formate, both of which are fragrance raw materials. Therefore, one fragrance raw material is used to prepare a releasable form (pro-accord) of two fragrance raw materials.
The pro-accord 3,7-dimethyl-1,6-octadien-3-yl 3-(naphthyl)-3-oxo-propionate, which is a xcex2-ketoester pro-accord, is prepared by treating 3,7-dimethyl-1,6-octadien-3-ol (linalool), which is a fragrance raw material according to the present invention, with diketene under suitable conditions to form intermediate 3,7-dimethyl-1,6-octadien-3-yl 3-oxo-butyrate, which is subsequently treated with 2-naphthoyl chloride to yield the pro-accord. 3,7-Dimethyl-1,6-octadien-3-yl 3-(xcex2-naphthyl)-3-oxo-propionate when exposed to suitable conditions (e.g., exposure to nascent moisture) breaks down to release a mixture of linalool and methyl xcex2-naphthyl ketone, both of which are fragrance raw materials as defined herein.
As described herein above, an optional component of the fragrance delivery systems of the present invention are pro-fragrances or pro-accords which are not heterocyclic aldehyde and/or ketone releasing pro-fragrances. The optional pro-accords or pro-fragrances are equally functional in either personal care compositions inter alia lotions, creams, deodorants or personal fragrance compositions inter alia fine fragrances, perfumes.
Preferred optional pro-accords and/or pro-fragrances include, but are not limited to, orthoesters, orthocarbonates, acetals, ketals, ortholactones, and xcex2-ketoesters.
Non-limiting examples of optional orthoesters which are suitable for use in the fragrance delivery systems of the present invention include tris-geranyl orthoformate, tris(cis-3-hexen-1-yl)orthoformate, tris(phenylethyl)orthoformate, bis(citronellyl)ethyl orthoacetate, tris(citronellyl)orthoformate, tris(cis-6-nonenyl)orthoformate, tris(phenoxyethyl)orthoformate, tris(geranyl,neryl)orthoformate (70:30 geranyl:neryl), tris(9-decenyl)orthoformate, tris(3-methyl-5-phenylpentanyl)orthoformate, tris(6-methylheptan-2-yl)orthoformate, tris([4-(2,2,6-trimethyl-2-cyclohexen-1-yl)-3-buten-2-yl]orthoformate, tris[3-methyl-5-(2,2,3-trimethyl-3-cyclopenten-1-yl)-4-penten-2-yl]orthoformate, trismenthyl orthoformate, tris(4-isopropylcyclohexylethyl-2-yl)orthoformate, tris-(6,8-dimethylnonan-2-yl)orthoformate, tris-phenylethyl orthoacetate, tris(cis-3-hexen-1-yl)orthoacetate, tris(cis-6-nonenyl)orthoacetate, tris-citronellyl orthoacetate, bis(geranyl)benzyl orthoacetate, tris(geranyl)orthoacetate, tris(4-isopropylcyclohexylmethyl)orthoacetate, tris(benzyl)orthoacetate, tris(2,6-dimethyl-5-heptenyl)orthoacetate, bis(cis-3-hexen-1-yl)amyl orthoacetate, and neryl citronellyl ethyl orthobutyrate.
Non-limiting examples of optional orthocarbonates which are suitable for use in the fragrance delivery systems of the present invention include bis(ethyl) bis(geranyl)orthocarbonate, bis(ethyl) bis(phenylethyl)orthocarbonate, bis(ethyl) bis(cis-3-hexenyl)orthocarbonate, bis(ethyl) bis(citronellyl)orthocarbonate, bis(ethyl) bis(linalyl)orthocarbonate, bis(ethyl) bis(menthyl)orthocarbonate, bis(dodecyl) bis(geranyl)orthocarbonate, and bis(dodecyl) bis(phenylethyl)orthocarbonate.
Non-limiting examples of optional acetals which are suitable for use in the fragrance delivery systems of the present invention include bis(cis-3-hexenyl)vanillin, bis(geranyl)cinnamaldehyde acetal, bis(2-phenylethyl)anisaldehyde acetal, bis(citronellyl)cyclamen aldehyde acetal, and bis(citronellyl)citral acetal.
Non-limiting examples of optional ketals which are suitable for use in the fragrance delivery systems of the present invention include bis(linalyl)xcex2-ionone ketal, bis(dihydromyrcenyl)xcex1-damascone ketal, bis(linalyl)6,7-dihydro-1,1,2,3,3-pentamethyl-4(5H)-indanone ketal, bis(dihydromyrcenyl)xcex2-ionone ketal, and bis(citronellyl)cis-jasmone ketal.
Non-limiting examples of optional xcex2-ketoesters which are suitable for use in the fragrance delivery systems of the present invention include 2,6-dimethyl-7-octen-2-yl 3-(4-methoxyphenyl)-3-oxo-propionate, 3,7-dimethyl-1,6-octadien-3-yl 3-(xcex1-naphthyl)-3-oxo-propionate, 2,6-dimethyl-7-octen-2-yl 3-(4-methoxyphenyl)-3-oxo-propionate, cis 3-hexen-1-yl 3-(xcex2-naphthyl)-3-oxo-propionate 2,6-dimethyl-7-octen-2-yl 3-(nonanyl)-3-oxo-propionate, 2,6-dimethyl-7-octen-2-yl 3-oxo-butyrate 3,7-dimethyl-1,6-octadien-3-yl 3-oxo-butyrate, 2,6-dimethyl-7-octen-2-yl 3-(xcex2-naphthyl)-3-oxo-2-methylpropionate, 3,7-dimethyl-1,6-octadien-3-yl 3-(xcex2-naphthyl)-3-oxo-2,2-dimethylpropionate, 3,7-dimethyl-1,6-octadien-3-yl 3-(xcex2-naphthyl)-3-oxo-2-methylpropionate, 3,7-dimethyl-2,6-octadienyl 3-(xcex2-naphthyl)-3-oxo-propionate, and 3,7-dimethyl-2,6-octadienyl 3-heptyl-3-oxo-propionate.
An example of a fragrance delivery system according to the present invention comprises:
a) from about 0.1% by weight, of a xcex2-amino ketone pro-fragrance, for example, 1-(2,6,6-trimethyl-3-cyclohexen-1-yl)-3-N,N-bis(5-hydroxy-3-oxapentyl)-1-butanone;
b) from about 0.2% by weight, of one or more aldehyde releasing pro-fragrances, for example, 2-(6-methyl-5-hepten-2-yl)-3-(1-methylethyl)-4-oxazikudubecarboxylic acid methyl ester, 2-(2,4-dimethyl-3-cyclohexen-1-yl)-3-(1-methylethyl)4-oxazolidinecarboxylic acid methyl ester;
c) optionally from about 0.1% by weight, of one or more alcohol releasing pro-fragrances; preferably an alcohol releasing pro-accord, for example, geranyl orthoformate;
d) from about 0.1% by weight, of one or more fragrance raw materials, for example, lillial, xcex3-decalactone;
e) optionally, from about 1% by weight, of pre-blended perfume ingredients of fragrance raw material accords; and
f) the balance carriers.
A non-limiting example of an alcohol releasing pro-accord admixture which is suitable for use in the fragrance delivery systems of the present invention comprises:
i) from about 0.5% to about 5% by weight, of nonadyl orthoformate;
ii) from about 1.5% to about 5% by weight, of mugetanol orthoformate;
iii) from about 1.5% to about 5% by weight, of osyrol orthoformate; and
iv) from about 1% to about 10% by weight, of benzyl orthoacetate.
One aspect of the present invention which is a key element in providing the formulator with a method for determining the manner in which a pro-fragrance according to the present invention releases its fragrance raw material, is the measurement of the pro-fragrance xe2x80x9cFragrance Release Half-Life, (FRHL). The pro-fragrances useful in the personal care compositions of the present invention generally have a delayed release of final fragrance raw material in order to achieve the increased fragrance longevity benefits described herein. However, the pro-fragrances generally also deliver the fragrance raw materials during a time period useful to the formulator, for example, within a time period desirable to the consumer.
For the purposes of the present invention the pro-accords generally have a FRHL of less than or equal to 12 hours when measured in NaH2PO4 buffer at pH 2.5 and greater than or equal to 0.1 hour when measured in NaH2PO4 buffer at pH 5.3. The xe2x80x9cFragrance Release Half-lifexe2x80x9d is defined herein as follows.
Pro-fragrances deliver their corresponding mixture of fragrance raw materials or fragrance accords according to the equation:
Pro-Fragrancexe2x86x92Fragrance Raw Material
wherein the fragrance raw material which is released may be released as a single component or a multiple fragrance raw material accord.
The rate at which the fragrance is released is defined by the formula:
Rate=k[Pro-fragrance]
and can be further expressed by the formula:       -                  ⅆ                  [Pro-fragrance]                            ⅆ        t              =      k    ⁢          [Pro-fragrance]      
wherein k is the release rate constant and [Pro-fragrance] is the concentration of pro-fragrance. For the purposes of the present invention the xe2x80x9cFragrance Release Half-lifexe2x80x9d, t1/2, is related to the release rate constant by the formula:       t          1      /      2        =      0.693    k  
and this relationship is used for the purposes of the present invention to determine the xe2x80x9cFRHL.
Due to the hydrophobic nature of some pro-accords, it is necessary to conduct the determination of t1/2 and k in a mixture of 90/10 dioxane/phosphate buffered water. The phosphate buffered water is prepared by admixing 3.95 mL of 85% phosphoric acid (H3PO4) and 24 g of sodium dihydrogen phosphate (NaH2PO4) with one liter of water. The pH of this solution is approximately 2.5. Next 10 mL of the phosphate buffer is admixed with 90 mL of dioxane and the pro-fragrance to be analyzed is added. The hydrolysis kinetics are then monitored by conventional HPLC at 30xc2x0 C.
In some instances, it is desirable to formulate a fragrance delivery system having one or more pro-fragrances which deliver a rapid release of fragrance raw material in addition to the delayed onset of a fragrance. In such cases the hydrolysis rate, and therefore the determination of t1/2 must be measured in a buffer system which can accommodate this more rapid hydrolysis rate.
The pro-fragrances of the present invention are stable under pH conditions encountered in the formulation and storage of fine perfume, personal care and personal hygiene articles which have a pH of from about 7.1 to 11.5, and during solution-use of such products. Due to their high molecular weight and hydrophobicity, these pro-fragrances and/or pro-accords remain deposited upon skin even when exposed to water (i.e. when formulated into a sun screen). Because the pro-fragrances are subject to hydrolysis when the pH is reduced, they hydrolyze to release their component fragrance compounds when applied to skin or are exposed even to reduced pH such as present in air and humidity. The reduction in pH should be at least 0.1, preferably at least about 0.5 units. Preferably the pH is reduced by at least 0.5 units to a pH of 7.5 or less, more preferably 6.9 or less. Preferably, the solution in which the pro-accord is applied is alkaline.
The pro-fragrances of the present invention typically have an Odor Value greater than or equal to about 1, preferably greater than or equal to about 5, more preferably greater than or equal to about 10. The term xe2x80x9cOdor Valuexe2x80x9d is defined by the following formula:   OV  =                    [                  Concentration          ⁢                      xe2x80x83                    ⁢          of          ⁢                      xe2x80x83                    ⁢          FRM                ]            ⁢              xe2x80x83              ODT  
wherein OV is the odor value of the fragrance raw material released upon the skin by the pro-accord. The odor value is the concentration of the fragrance raw material, FRM, on the skin surface divided by the Odor Detection Threshold, ODT. The term xe2x80x9clevel of noticeabilityxe2x80x9d is often applied to and/or substituted for the term xe2x80x9codor valuexe2x80x9d.
For the purposes of the present invention the term xe2x80x9codor detection thresholdxe2x80x9d is defined as the level at which a fragrance raw material is perceptible to the average human. The odor detection threshold (ODT) of the compositions of the present invention are preferably measured by carefully controlled gas chromatograph (GC) conditions as described hereinbelow. The preferred fragrance raw materials of the present invention have an ODT of at least about 100 part per billion (ppb), more preferably 10 ppb, most preferably 1 ppb. Fragrance raw materials having an ODT greater than 10 parts per million (ppm) are typically avoided unless useful as an adjunct ingredient, for example, as an adjunct alcohol when adjusting the fragrance release half-life of an orthoester.
Determination of Odor Detection Thresholds is as follows. A gas chromatograph is characterized to determine the exact volume of material injected by a syringe, the precise split ratio, and the hydrocarbon response using a hydrocarbon standard of known concentration and chain-length distribution. The air flow rate in accurately measured and, assuming the duration of a human inhalation to last 0.02 minutes, the sampled volume is calculated. Since the precise concentration at the detector at any point in time is known, the mass per volume inhaled is known and hence the concentration of material. To determine whether a material has a threshold below 10 ppb, solutions are delivered to the sniff port at the back-calculated concentration. A panelist sniffs the GC effluent and identifies the retention time when odor is notice. The average over all panelists determines the threshold of noticeability or ODT. The necessary amount of analyte is injected onto the column to achieve a 10 ppb concentration at the detector. Typical gas chromatograph parameters for determining odor detection thresholds are listed below.
GC: 5890 Series II with FID detector 7673 Autosampler
Column: JandW Scientific DB-1, length 30 m, i.d. 0.25 mm, film thickness 1 xcexcm.
Split Injection: 17/1 split ratio
Autosampler: 1.13 xcexcl/injection
Column flow: 1.10 mL/min
Air flow: 345 mL/min
Inlet temperature: 245xc2x0 C.
Detector temperature: 285xc2x0 C.
Temperature Information:
Initial temperature: 50xc2x0 C.
Rate: 5xc2x0 C./min
Final temperature: 280xc2x0 C.
Final time: 6 min
Leading assumptions: 0.02 minutes per sniff and that GC air adds to sample dilution.
Although a pro-fragrance or pro-accord may comprise a fragrance release half-life which ensures delivery of a fragrance raw material during a period of time useful to the formulator, unless the fragrance raw materials which comprise said fragrance delivery system have ODT values large enough to be perceived by the user, the formulator will be compelled to use an inordinate amount of material to achieve a suitable fragrance level.
The pro-fragrances of the present invention have a Skin Performance Index (SPI) greater than or equal to 0.1, preferably greater than or equal to 0.5. The Skin Performance Index is defined by the following:   SPI  =                    [                  Odor          ⁢                      xe2x80x83                    ⁢          Value                ]            *              t              1        /        2            
wherein the term [Odor Value]* is the estimated concentration of the fragrance raw material in the headspace above a solution of the fragrance raw material as measured in a 1% solution of ethanol, and t1/2 is the fragrance release half-life measured at pH 5.3 in the above described buffer. For the purposes of the present invention, the t1/2 of the SPI is measured at 5.3 and the value of the fragrance release half-life is preferably from 0.1 hours to 60 hours.
The [Odor Value]* is an estimation of the vapor pressure of the fragrance raw material using empirically determined KOVATS indices. xe2x80x9cThe Vapor Pressures of Pure Substancesxe2x80x9d, T. Boublik et al., Elseiver, N.Y. (1973) incorporated herein by reference, describes an index line for normal alkanes wherein C10 is equal to 30,000 ppb, C12 is equal to 3,000 ppb, C14 is equal to 300 ppb, C16 is equal to 30 ppb, etc. Using these values as reference standards, the KOVATS index of a fragrance raw material is obtained from gas chromatographic analysis of the FRM and the experimental index is then used to determine the relative vapor pressure and hence the head space concentration of the fragrance raw material.
xe2x80x9cNew Method for Estimating Vapor Pressure by the Use of Gas Chromatographyxe2x80x9d J. Chromatography A, 79 p 123-129, (1996) and xe2x80x9cSimple and Versatile Injection System for Capillary Gas Chromatographic Columns: Performance Evaluation of a System Including Mass Spectrometric and Light Pipe Fourier-Transform Infrared Detectionxe2x80x9d, J. Chromatography A, 713, p 201-215, (1996) included herein by reference, further describe methods and techniques suitable for use in determining the vapor pressure and head space concentration of FRM""s as they relate to the term [Odor Value]* of the present invention.
Using the criteria set forth in the present invention inter alia fragrance release half-life, odor value, odor detection threshold, skin performance index, the formulator is able to fashion an aldehyde or ketone releasing cyclic pro-fragrance. By manipulation of the R2, R3, R4, R5 and R6 units of the cyclic pro-fragrances of the present invention the release rate of either an aldehyde or ketone fragrance raw material can be adjusted. Several different pro-fragrances which release the same fragrance raw material, but at differing rates or levels, can be admixed to further prolong or extend the period of fragrance raw material delivery.
When present, the carriers, fixatives, or stabilizers will comprise the balance of the compositions. Typical carriers are methanol, ethanol (preferred), iso-propanol, polyethylene glycol, as well as water in some instances, especially as a vehicle to deliver materials which provide reserve alkalinity to the fragrance delivery system. Fixatives serve to lower the volatility of certain top and middle notes in order to extend their contact time on skin. Adjunct ingredients include perfume raw material components which are essential oils and are therefore not a single chemical entity. In addition, the adjunct ingredients may be mixtures of materials which serve a purpose in addition to providing a pleasurable odor (i.e., an astringent in a personal hygiene article).
The formulators, in addition to selected fragrance raw materials, can combine a pre-blended fragrance with the pro-fragrances of the present invention. For the purposes of the present invention the term xe2x80x9cpre-blended fragrancexe2x80x9d is defined as an existing fragrance accord, commercially available or otherwise, which is enhanced by or in turn enhances the fragrance delivered by the pro-fragrances and/or pro-accords which comprise the balance of the fragrance delivery system. For example, an existing fragrance accord may be suitable in the short term but due to differential evaporation of the most volatile components, high notes, inter alia, the fragrance diminishes or the bouquet shifts. Therefore, pro-fragrances and pro-accords are combined which will release said volatile components thereby sustaining the complete fragrance accord.